In medical practice, a wide variety of antibiotics and synthetic antibacterial agents have been used for the treatment of infectious diseases. However, resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and penicillin-resistant Streptococcus pneumoniae (PRSP) have recently emerged. The treatment of patients infected with such a resistant organism has been a critical concern. In addition, multiresistant organisms that acquired resistance to multiple drugs have emerged. Infectious diseases caused by multiresistant organisms have been major problems worldwide as intractable diseases.
The appearance of antimicrobial agents which are effective against these resistant organisms has been strongly desired, and, for example, a quinolone compound considered to be effective against MRSA is disclosed in WO 99/07682 (PATENT DOCUMENT 1). Further, the compounds disclosed in WO 2004/002490 (PATENT DOCUMENT 2) and WO 2004/002992 (PATENT DOCUMENT 3) are known as the compounds having action mechanisms different from those of the existing drugs.    PATENT DOCUMENT 1: International Patent Publication No. WO 99/07682 pamphlet    PATENT DOCUMENT 2: International Patent Publication No. WO 2004/002490 pamphlet    PATENT DOCUMENT 3: International Patent Publication No. WO 2004/002992 pamphlet